Battery protection for PCF85263A

[fransjanvandons]

Does a battery (CR2032 button cell) need extra protection like a diode and current limiting resistor when this battery is connected to the PCF85263A? The explanation of the battery switch circuit inside the PCF85263A is very minimal.

Additional question: What is the leakage current on VBAT when VDD is active?

The typical application (datasheet):

Needed according to UL:

Proposed application:

Thanks,

Frans Jan

[TomasVaverka]

Hello Frans Jan,

Please refer to the UM10301 (Chapter 13) with a detailed description of this topic.

Best regards,

Tomas

[ehwsma]

Hi Tomas,

We have the same question here. The PCF85263A has an integrated battery switch-over and is UL Recognized but we have no details regarding the internal protections.

Details in UM10301 seems to be related to non-integrated switching circuit and it is therefore logical to add external protections, but the PCF85263A already incorporate some features.

Furthermore, Application diagram for PCF85263A doesn't include external protections while UM10301 recommends to add external protection. What do we have to do ?

Is it possible to get additional details? In which configuration was it tested when doing the UL certification ?

Thanks in advance.

[pietersimons]

Hello Tomas;

I''m interested in the PCF85263A too.

In UM10301 is stated on page 30:

All RTCs in this manual incorporate neither a dedicated switch-over circuit nor a charger and therefore this has to be realized with some external components.

The PCF85263A has a switch over circuit.

What is the leakage current on VBAT when VDD is active?